Cooling system for brakes

ABSTRACT

An improved cooling system for devices such as brakes is provided comprising a fluid-flow circuit including a pumping subcircuit and a closed-loop cooling sub-circuit. The pumping circuit includes a pump for circulating fluid through the fluidflow circuit, a siphon for initiating a high-volume fluid flow in the cooling circuit, and a valve for controlling fluid flow throught the siphon; the cooling circuit includes serially connected brakes and cooling means. When brake-cooling flow requirements are low, fluid is circulated primarily in the pumping circuit. Increase brake-cooling flow requirements actuate the valve, increasing the fluid flow through the syphon to initiate a high-volume fluid flow through the cooling circuit, thereby cooling the brakes. The system permits the use of a reduced capacity pump to satisfy the brake cooling flow requirements. Preferably, the fluid flow circuit also includes flowmaintaining means for preventing complete unloading of the output of the pump and maintaining a minimum volume of fluid flow within the cooling circuit to prevent fluid stagnation therein.

United States atent 1 1 Schexnayder 1 May 13, 1975 COOLING SYSTEM FOR BRAKES [57] ABSTRACT [75] Inventor: Lawrence F. Schexnayder, Joliet, Ill. An improved cooling system for devices such as [73] Assignee: Caterpillar Tractor Company, g provlqed g P l f g "Cult "1' Peoria [IL u mg a pumpmg su -c1rcu1t an a c ose oop coo mg sub-clrcuit. The pumpmg c1rcu1t includes a pump [22] Filed: Nov. 1, 1973 for circulating fluid through the fluid-flow circuit, a siphon for initiating a high-volume fluid flow in the [2]] Appl' L776 cooling circuit, and a valve for controlling fluid flow throught the siphon; the cooling circuit includes seri- [52] US. Cl. 165/40; 165/107; 303/1; ally connected brakes and cooling means. When 417/79; 417/186; 417/187; 417/182 brake-cooling flow requirements are low, fluid is cir- [51] Int. Cl. F28d 15/00 culated primarily in the pumping circuit. Increase [58] Field of Search 165/107, 40; 417/79, 186, brake-cooling flow requirements actuate the valve, in-

417/187, 182; 336/57 creasing the fluid flow through the syphon to initiate a high-volume fluid flow through the cooling circuit. [56] References Cited thereby cooling the brakes. The system permits the UNITED STATES PATENTS use of a reduced capacity pump to satisfy the brake 611,081 9/1898 Schneible 417/187 x Coohng flow requremems- 1,706,574 3/1929 Hodtum 165/107 X Preferably, the fluid flow circuit also includes 1,798,702 3/1931 Proebel 165/107 flow-maintaining means for preventing complete unloading of the output of the pump and maintaining Primary Examiner-Albert Davis, a minimum volume of fluid flow within the cooling A r y, g FirmPhilliP$, Moore, circuit to prevent fluid stagnation therein. Weissenberger, Lempio & Strabala 9 Claims, 1 Drawing Figure if 32 1g i4 86 1 21 35 a? A B g4 43 5 1 -11 p 22 1 :29 j 41 w l 1| IT; 27 21 RESERVOIR l 28 26 l l 16 19 1 COOLING SYSTEM FOR BRAKES BACKGROUND OF THE INVENTION This invention relates to an improved cooling system for diffusing heat generated by a heat source. In particular, this invention relates to an improved system for dissipating heat of friction generated within the braking systems of vehicles such as earthmoving vehicles.

Conventionally, such cooling systems, particularly those for disc brakes, comprise a fluid flow circuit serially interconnecting the brake housing and a cooling means for cooling fluid heated within the brake housing. Fluid such as oil is pumped through this circuit by pumping means actuated by a prime mover, accumulating heat within the brake housing and dissipating this heat by the cooling means. This brake cooling circuit normally requires a high volume flow of fluid at relatively low pressures, since the volume of fluid circulated within the brake housing and cooling means is directly related to the cooling capacity of the system.

In order to maintain an adequate fluid volume and flow rate, pump means large enough in capacity to directly supply the requirements of the brake cooling system have typically been employed. Such systems have,

however, placed a heavy burden on the prime mover, since the attendant horsepower requirements are frequently substantial.

Although attempts have been made to minimize this problem, they have not always been successful. For example, it has been found to be desirable to unload the pump means when heat is at a sufficiently low level within the braking system, and fluid flow requirements are therefore minimal. Numerous methods have been proposed for unloading the pumping means, thereby freeing the prime mover for other work, but it has proved difficult to unload the large capacity pumps presently in use, due primarily to the relatively large valve components thereof. Additionally, whenever complete unloading of the pump means has been accomplished, it has been found that stagnation tends to occur within the circuit in the absence of fluid flow, with the concomitant disadvantages.

SUMMARY AND OBJECTS OF THE INVENTION Accordingly, the invention broadly provides a cooling system for cooling a source of heat energy comprising circulating fluid through a fluid flow circuit including a source of heat energy and cooling means for cooling heated fluid, so that heataccumulated by the fluid circulating through the heat source is dispersed as the fluid flows through the cooling means. The fluid flow circuit generally comprises two sub-circuits including a closed-loop cooling circuit, and a pumping circuit provided with a relatively small-capacity pump. The output of this pump directed through syphon or ejector means included in the fluid-flow circuit creates a highvolume fluid flow in the closed loop cooling circuit, thereby satisfying flow requirements for cooling the heat source with a substantial reduction in the usual size of the pumping means. There is a concomitant reduction in the power required to operate the pumping means, and thus the power requirements normally placed on the prime mover by the flow requirements of the cooling system are effectively reduced. Additionally, the cooling system herein provided is relatively inexpensive in terms of both capital and operating costs, while at the same time the reduced capacity pump means of the system facilitates control of the pump means and fluid flow within the system.

The cooling system of this invention further includes flow-maintaining means for maintaining a minimum predetermined volume of flow within the fluid-flow circuit, thereby preventing complete unloading of the output of the pumping means and preventing fluid stagnation within the circuit.

It is therefore an object of this invention to provide a cooling system for efficiently cooling a source of heat energy having reduced-capacity pumping means for circulating a high volume of cooling fluid through the system.

It is another object of this invention to provide a cooling system for efficiently cooling a source of heat energy including pumping means having a low power requirement for a high volume of cooling circulating fluid through the system.

It is an additional object of this invention to provide a cooling system for efficiently cooling a source of heat energy including reduced-size pumping means for circulating a high-volume of cooling fluid within the sys- -tem, whereby control of fluid flow and the pumping means is facilitated. 1

It is a further object of this invention to provide a cooling system for cooling a source of heat energy wherein a minimum volume of fluid is constantly circulated in the system during operation thereof, thereby preventing fluid stagnation with the system.

It is yet another object of this invention to provide a cooling system for efficiently cooling a source of heat energy which is relatively inexpensive in terms of both capital and operating costs.

It is still another object of the invention to provide a efficient brake cooling system having reducedcapacity, low-power pumping means for circulating a high volume of cooling fluid through the system.

Other objects'and advantages of the invention will become apparent from the following description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The sole FIGURE is a schematic diagram of the cooling system of this invention.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawing, the cooling system of this invention, hereinafter referred to as a brake cooling system includes a fluid flow circuit generally indicated at 10 having a pumping sub-circuit generally indicated at 11, and a closed loop cooling sub-circuit generally indicated at 12. The pumping sub-circuit 11 includes reduced-capacity pump or pumping means 13 which is drivingly corinected to a prime mover not shown for pumping oil or other fluid through the fluid flow circuit 10, The pumping circuit 11 further includes valve means in the form of a valve 14 for controlling fluid flow within the fluid flow circuit 10. Valve 14 is shown as an unloading or dump valve communicating with reservoir means 16 for storing reserve fluid when the output of pump 13 is unloaded and circulating fluid volume within the fluid flow circuit is reduced.

The cooling circuit 12 includes a brake housing 17 and cooling means such as a heat exchanger 18 for dispersing heat from the heated fluid flowing from brake housing 17.

The fluid flow circuit is provided at a junction of pumping circuit 11 and cooling circuit 12 with ejector or siphon means 19 for initiating a high volume of flow in the cooling circuit 12 in response to high velocity fluid flow through a jet 21 of siphon means 19. The siphon means 19 operates in the conventional manner; that is, a high velocity flow through the jet 21 creates suction in the area surrounding the jet and in an intake 22 of a conduit 23 of the cooling circuit 12. Fluid is thereby drawn through the cooling circuit and combined with fluid from the pumping circuit 11; this high volume of fluid is then circulated by way of a conduit 24 of cooling circuit 12 through the brake housing 17, where it accumulates friction heat generated by braking action, and then through cooling means 18, where the accumulated heat is transferred and dispersed into the atmosphere.

When heat levels within the brake housing 17 are sufficiently low so that a high volume of fluid flow is not required for cooling, the valve means 14 adjusts to direct the fluid flowing within the fluid flow circuit 10 to the reservoir means 16, thereby further substantially reducing power requirements for the system. In the embodiment of the invention illustrated, the fluid flow circuit 10 further includes flow-maintaining means 26 for maintaining a predetermined minimum rate of flow through the cooling circuit 12 when the output of pump 13 is unloaded, thereby preventing fluid stagnation within the circuit. The flow-maintaining means illustrated comprise a conduit 27 interconnecting valve 14 and reservoir means 16 having a constricted venturi portion 28. Fluid circulating in pumping circuit 11, through valve 14 and into reservoir means 16, will thus be obstructed by the constricted portion 28 of conduit 27, and the resulting build-up of fluid pressure within the pumping circuit 11 will force a portion of the fluid through siphon means in the form of a jet pump 19 into cooling circuit 12. A continuous circulation of fluid through cooling circuit 12 is thereby obtained, and stagnation of fluid within the cooling circuit prevented. Preferably, means such as a conduit 29 interconnecting reservoir means 16 and cooling circuit 12, are provided for replenishing cooling circuit 12 with fluid when necessary to maintain the desired minimum fluidvolume within the circuit.

Advantageously, filter means 31 are provided within pumping circuit 11 for removing contaminants from the circulating fluid. Also, it is desirable to provide the fluid flow circuit 10 with means for relieving the circuit from excessively high fluid pressures, such as pressure relief valve means 32, disposed in a conduit 33 interconnecting reservoir means 16 and a conduit 34, which interconnects pumping means 13 and filter means 31. Pressure relief valve or means 32 responds to an excessive increase in fluid pressure within fluid flow circuit 10 caused, for example, by clogged orifice 21, by opening to allow fluid flow through conduit 33 into reservoir means 16, thereby relieving the system of excessive pressure.

In the embodiment of the invention illustrated, valve means 14 is adapted to respond to an increase in temperature within brake housing 17 through a valveregulating means 35 for regulating the disposition of the valve means 14 and thus the flow of fluid through the fluid flow circuit 10. Regulating means 35 includes a temperature sensor 36, and a control valve 37 provided with a solenoid or other switch means 38. The

temperature sensor 36 is located in brake housing 17 and is set to send an electrical signal to the solenoid 38 when a predetermined high temperature is reached within the brake housing. The control valve 37 directly communicates between valve means 14 and reservoir means 16 by way of a conduit 39, and is actuated by the solenoid 38. When a signal is received by the solenoid 38 that the predetermined temperature has been reached in the brake housing 17, the control valve 37 is actuated to flow-restricting position A, where it is maintained against a biasing spring 41, until the signal from the temperature sensor 36 is terminated, indicating that temperatures within the brake housing 17 have fallen below the predetermined level. Biasing spring 41 then shifts the control valve 37 to the flow-permitting position B, causing fluid to flow from a chamber 42 of valve means 14 through the conduit 39 into reservoir means 16. Fluid flowing through a conduit 43 of pumping circuit 1 1 acts on a shoulder 44 of a dump valve element 46, thereby shifting the valve element 46 against a second biasing spring 47, and unseating it from seat 48 and permitting fluid to flow from the conduit 43 into the conduit 27 interconnecting the valve means 14 and the reservoir means 16. As hereinbefore described, the flow rate from the conduit 39 into the reservoir means 16 is preferably controlled as by the constricted portion 28 of the conduit 27.

In order to make power available to other systems as required, it is desirable to provide means for manually overriding the automatic valve regulating means and shifting the control valve 37 to permit fluid flow from pumping circuit 11 into reservoir means 16 via the conduit 39. This may, however, result in an increase in temperature within the brake housing 17 over the predetermined maximum until fluid flow is restored, and caution must be exercised.

In the specific embodiment illustrated, a pump 13 having an output of about 15 gallons per minute is sufficient to produce a flow of about l50 gallons per minute through the cooling circuit 12. It may thus be seen that the cooling system of this invention provides means for obtaining a high volume fluid flow through a fluid flow circuit by reduced-capacity pumping means, substantially decreasing typical power requirements. Further, since the pumping circuit 11 accommodates approximately 10% of the flow of the cooling circuit 12, it is apparent that the respective valve means and conduits may be relatively small, thus resulting in a more economical system.

In view of the foregoing, it should be apparent that the present invention provides a vastly improved cooling system for cooling a source of heat energy within a fluid-flow circuit, and in particular provides an improved brake cooling system. While the invention has been described with particular reference to the pre ferred embodiment, it is apparent that variations and modifications are possible within the preview of the inventive concepts. No limitation with respect to such variations or modifications is intended, except by the scope of the appended claims.

What is claimed is:

1. A cooling system comprising a fluid flow circuit including a pumping sub-circuit, a closed loop cooling sub-circuit, and siphon means interconnecting the pumping and cooling sub-circuits for initiating highvolume fluid flow within the cooling sub-circuit in response to increased fluid flow from said pumping subcircuit into said siphon means, said pumping sub-circuit including pumping means for circulating fluid within said fluid flow circuit, valve means for controlling fluid flow into said siphon means and reservoir means for storing reserve fluid, and said cooling sub-circuit including heat generating means and cooling means for cooling fluid heated by said heat generating means, said fluid circulating at least primarily within said pumping sub-circuit when cooling flow requirements are sufficiently low, said valve means including a dump valve and said actuating means including control valve means disposed between said dump valve and said reservoir means for regulating fluid flow from said dump valve into said reservoir means whereby adjustment of said control valve means to evacuate fluid from said dump valve into said reservoir increases fluid flow into said siphon means, wherein said fluid flow circuit further includes temperature-sensitive actuating means for actuating said valve means to increase fluid flow into said siphon means in response to increased temperatures in said heat generating means, whereby high-volume fluid flow is initiated in said cooling sub-circuit by said siphon means.

2. The cooling system of claim 1, wherein said actuating means further includes temperature-responsive solenoid means for adjusting said control valve means to evacuate fluid from said dump valve in response to a predetermined temperature in said heat generating means.

3. The cooling system of claim 1, wherein the solenoid means is responsive thereof for actuation temperature sensor means within said housing.

4. The cooling system of claim 1, wherein said pumping circuit further includes flow-maintaining means for preventing complete unloading of the output of the pumping'means and maintaining a minimum rate of fluid flow through said cooling circuit during operation of said system to prevent fluid stagnation within said cooling circuit.

5. The cooling system of claim 4, wherein the flowmaintaining means includes a conduit interconnecting said valve means and said reservoir means having a constriction therein, whereby fluid flowing within said pumping sub-circuit through said valve means into said reservoir is obstructed, thereby creating pressure within said pumping sub-circuit and forcing a minimum volume of fluid through said siphon means into said cooling sub-circuit.

6. The cooling system of claim 5, wherein said fluid flow circuit further includes replenishing means for replenishing the fluid flow circuit with fluid from said reservoir means when fluid volume within said fluid flow circuit is sufficiently depleted, said replenishing means including a conduit interconnecting said reservoir means and said fluid flow circuit.

7. The cooling system of claim 1, wherein said pumping means includes a reduced-capacity pump having low power requirements for operation thereof.

8. The cooling system of claim 6, wherein said fluid flow circuit further includes filter means for filtering contaminants from fluid therewithin.

9. The cooling system of claim 8, wherein said fluid flow circuit further includes relief valve means disposed on a conduit interconnecting said pumping subcircuit and said reservoir means for admitting fluid from said pumping sub-circuit into said reservoir means in response to fluid overpressure within said pumping sub-circuit.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Q PATENT NO. 3,882,930

DATED y 3, 975

INVENTOR(S) Lawrence F. Schexnayder It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the Title Page, Item [73], change the spelling of the assignee's corporate name from "Caterpillar Tractor Company" to --Caterpillar Tractor Co.--.

Signed and Sealed this second Day Of Decemberl975 [SEAL] Attest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner qflarenrs and Trademarks 6 

1. A cooling system comprising a fluid flow circuit including a pumping sub-circuit, a closed loop cooling sub-circuit, and siphon means interconnecting the pumping and cooling sub-circuits for initiating high-volume fluid flow within the cooling subcircuit in response to increased fluid flow from said pumping sub-circuit into said siphon means, said pumping sub-circuit including pumping means for circulating fluid within said fluid flow circuit, valve means for controlling fluid flow into said siphon means and reservoir means for storing reserve fluid, and said cooling sub-circuit including heat generating means and cooling means for cooling fluid heated by said heat generating means, said fluid circulating at least primarily within said pumping sub-circuit when cooling flow requirements are sufficiently low, said valve means including a dump valve and said actuating means including control valve means disposed between said dump valve and said reservoir means for regulating fluid flow from said dump valve into said reservoir means whereby adjustment of said control valve means to evacuate fluid from said dump valve into said reservoir increases fluid floW into said siphon means, wherein said fluid flow circuit further includes temperature-sensitive actuating means for actuating said valve means to increase fluid flow into said siphon means in response to increased temperatures in said heat generating means, whereby high-volume fluid flow is initiated in said cooling subcircuit by said siphon means.
 2. The cooling system of claim 1, wherein said actuating means further includes temperature-responsive solenoid means for adjusting said control valve means to evacuate fluid from said dump valve in response to a predetermined temperature in said heat generating means.
 3. The cooling system of claim 1, wherein the solenoid means is responsive thereof for actuation temperature sensor means within said housing.
 4. The cooling system of claim 1, wherein said pumping circuit further includes flow-maintaining means for preventing complete unloading of the output of the pumping means and maintaining a minimum rate of fluid flow through said cooling circuit during operation of said system to prevent fluid stagnation within said cooling circuit.
 5. The cooling system of claim 4, wherein the flow-maintaining means includes a conduit interconnecting said valve means and said reservoir means having a constriction therein, whereby fluid flowing within said pumping sub-circuit through said valve means into said reservoir is obstructed, thereby creating pressure within said pumping sub-circuit and forcing a minimum volume of fluid through said siphon means into said cooling sub-circuit.
 6. The cooling system of claim 5, wherein said fluid flow circuit further includes replenishing means for replenishing the fluid flow circuit with fluid from said reservoir means when fluid volume within said fluid flow circuit is sufficiently depleted, said replenishing means including a conduit interconnecting said reservoir means and said fluid flow circuit.
 7. The cooling system of claim 1, wherein said pumping means includes a reduced-capacity pump having low power requirements for operation thereof.
 8. The cooling system of claim 6, wherein said fluid flow circuit further includes filter means for filtering contaminants from fluid therewithin.
 9. The cooling system of claim 8, wherein said fluid flow circuit further includes relief valve means disposed on a conduit interconnecting said pumping sub-circuit and said reservoir means for admitting fluid from said pumping sub-circuit into said reservoir means in response to fluid overpressure within said pumping sub-circuit. 